Doherty amplifier

Abstract

The present invention relates to the construction of output stage of the Doherty amplifier and comprises a main amplifying unit, an auxiliary amplifying unit and a compact λ/4 line connecting two amplifying units. The compact λ/4 line connecting two amplifying units includes a first parallel capacitor grounded by being connected to the main amplifying unit in parallel; a second parallel capacitor grounded by being connected to the auxiliary amplifying unit in parallel; and an inductor or a microstrip transmission line connecting the main amplifying unit and the auxiliary amplifying unit. The Doherty amplifier in accordance with the present invention further comprises a matching network unit connecting to a final output by connecting the main amplifying unit and the auxiliary amplifying unit and; and a λ/4 line used as the voltage inputs of the main amplifying unit and the auxiliary amplifying unit.

1. A Doherty amplifier provided with a main amplifying unit and an auxiliary amplifying unit, comprising:
 a first parallel capacitor grounded by being connected to the main amplifying unit in parallel; 
 a second parallel capacitor grounded by being connected to the auxiliary amplifying unit in parallel; 
 a transmission line unit connecting the main amplifying unit and the auxiliary amplifying unit and including one of an inductor and a microstrip transmission line; and 
 a λ/4 line applying voltage to the main amplifying unit and the auxiliary amplifying unit by being divided between the first parallel capacitor and the transmission line unit. 
 
   
   
     2. The Doherty amplifier as recited in  claim 1 , further comprising a matching network unit divided between the second parallel capacitor and the transmission line unit. 
   
   
     3. The Doherty amplifier as recited in  claim 1 , wherein the first parallel capacitor, the second parallel capacitor and the transmission line unit form a π-network type compact λ/4 line. 
   
   
     4. The Doherty amplifier as recited in  claim 2 , wherein the first parallel capacitor, the second parallel capacitor and the transmission line unit form a π-network type compact λ/4 line. 
   
   
     5. A Doherty amplifier provided with a main amplifying unit and an auxiliary amplifying unit, comprising:
 a first parallel impedance grounded by being connected to the main amplifying unit in parallel; 
 a second parallel impedance grounded by being connected to the auxiliary amplifying unit in parallel; 
 a transmission line unit connecting the main amplifying unit and the auxiliary amplifying unit and constructed by including a capacitor; 
 a first λ/4 line applying voltage to the main amplifying unit by being divided between the first parallel impedance and the transmission line unit; 
 a second λ/4 line applying voltage to the auxiliary amplifying unit by being divided between the second parallel impedance and the transmission line unit; and 
 a matching network unit divided among the auxiliary amplifying unit, the second parallel impedance and the transmission line unit. 
 
   
   
     6. A Doherty amplifier provided with a main amplifying unit and an auxiliary amplifying unit, comprising:
 a first parallel impedance grounded by being connected to the main amplifying unit in parallel; 
 a second parallel impedance grounded by being connected to the auxiliary amplifying unit in parallel; 
 a first harmonics suppression unit grounded by being connected to the main amplifying unit and the first parallel impedance in parallel to suppress the harmonics; 
 a second harmonics suppression unit grounded by being connected to the auxiliary amplifying unit and the second parallel impedance in parallel to suppress the harmonics; 
 a first inductor applying voltage to the main amplifying unit and the auxiliary amplifying unit by being divided among the auxiliary amplifying unit, the second parallel impedance and the second harmonics suppression unit; 
 a second inductor connecting the main amplifying unit and the auxiliary amplifying unit; and 
 a matching network unit divided between the second parallel capacitor and the second inductor. 
 
   
   
     7. A Doherty amplifier provided with a main amplifying unit and an auxiliary amplifying unit, comprising:
 a first matching network unit connected to the output stage of the main amplifying unit and matched so that the output of the main amplifying unit is an impedance of 100 Ω; 
 a second matching network unit connected to the output stage of the auxiliary amplifying unit and matched so that the output of the auxiliary amplifying unit is an impedance of 100 Ω; 
 a quarter-wave transmission line connected to the outputs of the first matching network unit and the second matching network unit with an impedance of 100 Ωgenerating final output by connecting the main amplifying unit and the auxiliary amplifying unit in parallel; 
 a first offset line connected to the output stage of the first matching network unit with an impedance of 100Ω; and 
 a second offset line connected to the output stage of the second matching network unit with an impedance of 100 Ω.